The Ego 1 V2 would make sense, I think you can buy just the battery, while keeping the tank you like, if it's functioning. If the new tank isn't drawing right, you can certainly switch out coils to see if you can find a vape you like.
If you want a box mod that's incredibly easygoing (if you don't mind too heavy), I'd suggest the Steampunk Tesla nano, it looks like a work of art (LOL, I said I'd never buy one, now it's all I want to recommend

) but it functions SO smoothly and it's easy to operate. I like heavy things (harder to drop) this isn't something that would really go in your pocket, though it is small for a box mod. It's got useful user functions and it vapes... better than any mod I've vaped before (but I've only tried a few, you may well get better recommendations). If you want a tight draw on your tank you could try the Nautilus 2 (you can color code to an extent, but it isn't going to look beautiful if you like matching things, by any means though I think mine looks... alright) but the Nautilus 2 has a very tight draw with the right coil, as well as a 0.7 coil which vapes smoothly at low wattage, and you can MTL inhale pretty easily on the right settings. That said, I think just a Nautilus 2 would fit on the Ego 2 stick without too much problems, and might look better and be less expensive. That way you can keep your old tank if you like it, or continue on with the Nautilus 2. I LOVE this tank, it has great flavor production and it's top fill, which is nice. Just don't overfill and close off the airholes if it's going in your pocket. I might try that, then see if you want a box mod later. The N2 comes with a 1.8 coil and a 0.7 coil, so you can try them both out, and I think the V2 stick is wattage adjustable, right? I have an Ego Mega and a 1.0 coil, I don't hate the vape by any means, but I LOVE the Nautilus (really just got the ego tank to try building with cotton and TC, first. I'm sure I'll warm up to it, but for a small tank *I* at least, cannot beat the N2, by Aspire.
Good luck.
Anna